1. Field of the Invention
The present invention relates to a Cu-based amorphous alloy composition having the possibility of the use for the structural material, which enhances the formability and the efficiency for bulk amorphism of Cu-based alloy.
2. Description of the Related Art
Most metal alloys, when they congeal from the liquid phase, form crystal phase where the atoms are arrayed regularly. However, if the quenching speed is faster than a critical value, the nucleation and the growth of the crystal phase can be limited and the irregular atomic structure of the liquid phase can be maintained in the solid phase. This kind of alloy is called as “amorphous alloy”. Amorphous alloy has tensile strength 2˜3 times larger than that of the crystalline alloy and, also, is superior in corrosion resistance because of its homogeneous structure without grain boundary.
Since the amorphous structure was reported on the Au—Si based alloy in 1960, many kinds of amorphous alloys have been invented and used. However, in case of most amorphous alloys, as the nucleation and the growth of the crystal phase proceed rapidly in the super-cooled liquid phase, very fast quenching speed is required for the prevention of the formation of the crystal phase during the cooling process from the liquid phase. Therefore, most amorphous alloys have been produced through “rapid quenching technique” with the quenching speed of 104˜106 K/s in the forms of ribbon with thickness less than 80 μm, fine line with diameter less than 150 μm or fine powder with diameter less than hundreds of μm. Further, the amorphous alloys, which are produced with the rapid quenching technique, have restriction in their shape and size, and so, we have difficulties in their commercialization. Therefore, it is required to develop the alloy with low critical quenching speed, which can avoid the formation of crystal phase during the cooling process from the liquid phase.
If the formability of amorphous alloy is excellent, the production of bulk amorphous alloy may be possible by means of a casting method. For example, for the manufacturing of amorphous alloy with about 1 mm thickness, crystallization should not occur even at the low quenching speed of 103 K/s. Besides the low quenching speed, “super-cooled liquid region” is an important factor for the production of bulk amorphous alloy in the industrial perspective. In the super-cooled liquid region, the viscous flow enables the formation of amorphous alloy, which makes it possible to manufacture articles with a certain shape from the amorphous alloy.
The amorphous alloys, which are Fe-based, Ti-based, Co-based, Zr-based, Ni-based, Pd-based, Cu-based and the like, have been developed till the present. Among the Cu-based alloys are the binary alloys of Cu-M (M=Ti, Zr or Hf), ternary alloys of Cu—Mg-Ln (Ln=La, Sm, Eu, Tb, Er or Lu), Cu—Zr—Ti, Cu—Hf—Ti and Cu—Zr—Al, and quaternary alloys of Cu—Zr—Hf—Ti, Cu—Zr—Ti—Y and Cu—Ti—Zr—Ni.
However, in the prior art, amorphous alloys were produced in the forms of ribbon or powder with thickness of dozens of μm with the “rapid quenching technique”. The recently developed Cu-based bulk amorphous alloys having maximum diameter of about 5 mm also have restrictions in the practical use.